1. Field of the Invention
The present invention relates to a method for preparing a solubilized composition containing an oil-soluble substance having both acid and heat resistance, the composition prepared by the method, and foods and drinks and cosmetics containing the composition. In particular, the present invention relates to a method for preparing a solubilized composition containing an oil-soluble substance, which is capable of keeping the oil-soluble substance in a uniform and stable solubilized state without its deposition or floating when a food and drink, or a cosmetic added with the composition is stored for a long time, and has both excellent acid and heat resistance necessary when being added to foods and drinks. The present invention also relates to the composition prepared by the method of the present invention, and foods and drinks and cosmetics containing the composition.
2. Description of the Related Art
In the fields of foods and drinks and cosmetics, commercial products in the liquid state at ambient temperature have been conventionally added with oil-soluble substances such as colorants, flavoring agents, oils and fats, fat-soluble vitamins, bioactive substances, seasonings, antioxidants, and preservatives. However, many of liquid preparations of foods and drinks and cosmetics are aqueous. To add an oil-soluble substance to these aqueous foods and drinks and cosmetics, there have been various known compositions and methods for preparing them. An example of the composition is an emulsion of an oil-soluble substance in an aqueous medium. Examples of the emulsion include: a carotenoid-based pigment-solubilized liquid preparation for foods capable of coloring aqueous foods and drinks (JP-A-10-120933); a composition containing a sucrose fatty acid ester, a C4-20 monohydric alcohol, an oily component, and water at a specific weight ratio (JP-A-10-43573 and JP-A-10-66860); a water-soluble composition containing a uniformly emulsified or solubilized oil and fat prepared by mixing an oil and fat and a lower alcohol solution containing at least one selected from the group consisting of monoesters of polyglycerols having a polymerization degree of 4 to 10 with capric acid, lauric acid, oleic acid and linoleic acid and an enzymatically decomposed lecithin with water or an aqueous solution of a sugar alcohol, and removing the lower alcohol from the mixture (JP-A-7-147899); an oil-and-fat-containing water-soluble composition in a emulsified or solubilized state containing at least one polyglycerol fatty acid ester selected from monoesters of polyglycerols having a polymerization degree of not less than 10 with C8-18 fatty acids, a sucrose fatty acid ester containing not less than 90% of a monoester of sucrose with a fatty acid, an oil and fat and residual parts of water (JP-A-8-205771); a solubilized oil and fat composition containing 0.003 to 50% by weight of at least one polyglycerol fatty acid monoester selected from monoesters of polyglycerol having an average polymerization degree of 6 to 10 with C12-14 saturated fatty acids, 0.05 to 20% by weight of an oil and fat, and residual parts of water and food additives (JP-A-9-168369); an oil-soluble substance-solubilized composition containing 0.01 to 30% by weight of a monoester of a polyglycerol fatty acid having an average polymerization degree of not less than 5 with myristic or oleic acid, 40 to 80% by weight of a polyhydric alcohol, 0.01 to 20% by weight of an oil-soluble substance, and residual parts of water (JP-A-10-084887); and an oil-soluble substance-solubilized composition containing (A) 0.05 to 30% by weight of an oil-soluble substance, (B) 0.003 to 50% by weight of polyglycerol fatty acid monoester of a polyglycerol having an average polymerization degree of 6 to 15 with a C12-18 saturated or monounsaturated fatty acid, (C) 0.0001 to 1% by weight of lecithin, and water (JP-A-11-332463). Any of methods for preparing these compositions includes emulsifying an oil-soluble substance in an aqueous medium, and fragmentating the oil-soluble substance into the nano-scale order with, for example, an emulsifying apparatus or a high-pressure homogenizer which applies strong shearing force. However, when the compositions prepared by the methods are added into cosmetics or foods and drinks, these cosmetics or foods and drinks do not sufficiently satisfy solubility, transparency, stability, heat resistance, and particularly acid resistance. In addition, the compositions are emulsions with aqueous media, and therefore have a compositional limitation on an amount added in commercial products.
There are known other methods for preparing an oil-soluble substance-solubilized composition, including preliminarily heating an oil-soluble substance and an emulsifier to form a uniform mixture, and adding the mixture to an aqueous medium (JP-A-7-100355, JP-A-10-182493, and JP-A-2004-339086). However, compositions prepared by the methods also do not satisfy solubility, transparency, stability, heat resistance, and acid resistance, when added to aqueous media.